In magnetic recording technology, it is constantly desired to improve the areal density at which information can be recorded and reliably read.
The magnetic recording head-disk assembly generally comprises a thin film disk on which data is stored, and a slider having a read and write head mounted thereon. The head generally comprises a bottom magnetic yoke layer, top magnetic yoke layer, magnetic insulating gap layer, coil layer, lower insulating layer for isolating the coil from the bottom magnetic yoke layer, and an upper insulating layer for isolating the coil from the top magnetic yoke layer. The topography of the head requires that the top magnetic yoke layer conforms over the coil structure and then converges onto the magnetic gap layer at an apex angle. The efficiency of the magnetic circuit of the film head is influenced by this apex angle.
U.S. Pat. No. 4,652,954 discloses a process for the manufacture of thin film magnetic heads. The process generally involves forming a first pole piece magnetic layer (bottom yoke layer) and then depositing a nonmagnetic gap layer on the first pole piece layer. A first polymeric photoresist insulating layer is then deposited onto the gap layer. The photoresist enables the formation of a back gap. Conductive coils are then formed on the first insulating layer, and a second polymeric photoresist insulating layer is disposed onto the coils. The head is then heated at a high temperature for a lengthy period of time to hard bake the photoresist into permanent insulating layers. During this heating step, the polymeric insulating layers flow to form gently sloping edges. Lastly, the second pole piece magnetic layer (top yoke layer) is formed on the insulating layers. The apex angle of the magnetic yoke (the angle formed by the intersection of the top yoke layer and gap layer) is defined by sloping edges of the insulating layers. In order to increase the write head efficiency, it is generally desired in the art to increase the apex angle of the magnetic yoke in thin film magnetic heads. It is also desired to achieve a hard bake of the photoresist at lower baking temperatures. It is therefore an object of the present invention to provide an improved thin film magnetic head and an improved process for making a thin film magnetic head.
Other objects and advantages will become apparent from the following disclosure and the drawing.